Micro-Strain and Temperature Sensors for Space Applications with Graphite-PDMS Composite

Abstract

Large-area flexible sensors have several applications [1]-[11]. In new generation aerospace systems, such flexible sensor sheets can be used to measure the spatial distribution of important parameters along the structure of launch-vehicles or space-crafts eg. Strain and temperature. Highly stretchable strains sensors have been developed using carbon-nanotube/PDMS composites [12], optical guides in PDMS [13], 3-D foam [14]. In [15], a method to adjust the sensitivity of strain sensors by tailoring the microstructure of graphene-aerogel/PDMS nanocomposite, in the strain range of 0 to 10%, has been discussed. Another work discusses flexible dual sensors (pressure and temperature) using microstructureframe-supported organic thermoelectric materials [16]. In this work, we investigate percolation based sensors with Graphite-PDMS (poly di-methyl siloxane) composites for measuring micro-strains and temperature. The concentration ratio of the graphite/elastomer and the dimensions, electrode spacing of the sensor have been experimentally optimized to operate the sensor in the micro-strain range (0-5000 μ.strain), which is of high interest in aerospace applications. The concentration ratio of Graphite/PDMS composite has been experimentally optimized as 0.46:0.54, and the PDMS Elastomer:Cross-linker ratio has been optimized as 4:1 to achieve sensitivity within this micro-strain range. Changes in both temperature and strain can be sensed by measuring the change in resistance across the electrodes of the sensing element. The fabrication methodology and the characterization measurements for micro-strain, temperature are further discussed in the subsequent sections

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